Public unions loathe the GOP governor, but private unions like his spending reforms and support for job creation.

New Jerseys gubernatorial race this year has attracted national attention thanks to the rising profile of Republican Gov. Chris Christie. Not as much attention has been paid to the rift between the Garden States private and public unions and what it could mean for the Democratic Party nationwide.

One reason Mr. Christie is 34 points ahead of his Democratic opponent in the latest poll is support from several dozen private unions that are traditional stalwarts of New Jersey Democrats. Their backing has alienated the states powerful public unions, which adamantly oppose Mr. Christie. The key issue dividing the labor movement is government spending and taxes.

Mr. Christie has secured labor support, especially among construction and trade unions, by emphasizing restraints on government spending, caps on tax increases, incentives for job creation, and vigorous rebuilding after Hurricane Sandy. Jobs are crucial in a state with an 8.5% unemployment rate. Mr. Christies message? "In four years, what Ive really cared about is how to get you guys back to work," he told the International Union of Operating Engineers in June.

The message resonates. When the International Brotherhood of Electrical Workers Local 102 endorsed the governor this year, "It was an easy call," said Patrick Delle Cava, the locals business manager. "Our men love him." He noted that the hours his members worked under the states two previous Democratic governors slumped to three million in 2009 from 6.5 million in 2001. Since Mr. Christie took office in early 2010, workers have regained nearly half.

The states labor movement heavily backed Democrat Jim McGreevey when he won the governorship in 2001. He rewarded unions with plumb initiatives, including a bill that sanctioned project labor agreements, which allow local governments to require union labor on some building projects. But he also raised state and local taxes. The Newark Star-Ledger estimated that in three years Mr. McGreevey raised 33 different taxes, a total increase of more than $3.6 billion.

Organized labor also backed Mr. McGreeveys successor, Democrat Jon Corzine in 2005, but union leaders representing private workers were growing restive. During budget negotiations in June 2006, Democratic State Senator Stephen Sweeney, an official with the International Association of Ironworkers, insisted that state workers take a 15% cut in wages and benefits to forestall further tax increases.

"My guys havent gotten a raise in two years because their entire raise went to their health and pension costs," Mr. Sweeney said. "New Jersey has a government that we cant afford any longer."

This drew a swift response from Bob Master of Communications Workers of America, which represents 35,000 state government workers. "This is frankly the kind of rhetoric we would expect from a right-wing Republican," he told the Philadelphia Inquirer. Mr. Corzine danced to the tune of the public unions, leaving state worker pay untouched and raising the sales tax to 7% from 6%.

Mr. Sweeney is now president of the state Senate, and he has helped Mr. Christie cut pension benefits for state workers and require greater retirement contributions. Mr. Christie reformed binding arbitration in municipal contracts, under which unelected mediators gave big pay boosts to public workers, by putting a cap on the size of awards. Hes balanced the state budget for three years without raising taxes.

The governors opponent, State Senator Barbara Buono, represents the leftward drift of the states Democratic Party. Shes voted dozens of times to raise taxes, she opposes fracking for natural gas, and she wants New Jersey to join the Regional Greenhouse Gas Initiative to lower CO2 emissions. The Sierra Club and Environmental Federation have endorsed her, which worries construction unions. "They are the two biggest enemies of any construction worker not only in the state of New Jersey but in the entire United States of America" Mike Mulvaney of a Steamfitters Union local told the Star-Ledger in June.

Government unions have tenaciously fought Mr. Christies attempts to trim the state budget, and this year they are all-in for Ms. Buono. Yet among voters without a college degree, Mr. Christie held a 30-point advantage over Ms. Buono in a Quinnipiac University poll last month. He is also winning about two-thirds of the states independent voters.

Mr. Christie has retained union support despite vetoing a bill in January to raise the minimum wage by $1.25 to $8.50. He also vetoed legislation this summer to let municipalities request bids only from all-union contractors when rebuilding after Sandy.

The larger question is what Mr. Christies appeal to labor might mean for his presidential aspirations. "One of the tectonic shifts in politics right now is the separation between some fiscal conservative Democrats and public-sector unions," says Pete Peterson, executive director of the Davenport Institute at Pepperdine University. Mr. Peterson points to battles in California cities between Democratic mayors and public labor groups over government budgets and worker benefits.

Mr. Christies labor success has generated some skepticism among conservatives who wonder what concessions he will make to his union backers. Rush Limbaugh has even speculated that labors embrace of Mr. Christie makes him a likely presidential candidate in 2016—for the Democrats.

Mr. Christie defends his reach across the aisle as practical politics. In a speech to GOP leaders in Boston last month, he argued that "for our ideas to matter, we have to win because, if we dont win, we dont govern." At least in New Jersey, Mr. Christie is on his way to winning.